Blade of a turbine

ABSTRACT

The present invention relates to a blade of turbine having an aerofoil, a platform and a root portion configured to be slidingly received in mounting slots of a rotor disc. The blade further includes a locking member disposed on the root portion and engaged with the rotor disc to make axial fixation of the blade to the rotor disc. With the technical solution of the present invention, it provides a blade with simple and cost effective axial locking system to make axial fixation of the blade relative to the rotor disc, and also a fail-safe solution during assembly process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to European application 13169635.3filed May 29, 2013, the contents of which are hereby incorporated in itsentirety.

TECHNICAL FIELD

The present invention relates to a turbine, in particular, to a blade ofturbine, more particularly, to a blade with a locking member to makeaxial fixation of the blade relative to the rotor disc.

BACKGROUND

A gas turbine has a rotor assembly which generally includes bladesattached to a rotor disc. Each blade comprises a root, a platform and anairfoil. The root of each blade is usually of a so-called “fir tree”configuration to enable it to be firmly attached to the periphery of thedisc and still have room for thermal expansion. The “fir tree”attachment of a blade to the rotor disc is effective in restraining theradial and circumferential movements of the blades, relative to therotor disc, against radial centrifugal forces. However, during highspeed, high temperature operation of the gas turbine engine, the axialflow of air or gas through the rotor assembly exerts a constant axialforce on the blades so as to bias the blade roots axially relative tothe “fir tree” slots in the periphery of the rotor disc. In order torestrain the blades against the axial force, it has been common practiceto employ various retention systems.

A conventional solution is applying a tab washer to fix the blade rootrelative to the slots in the rotor disc. However, the tab washer needsto be bent at assembly, which increases the complexity for the assemblyprocess and may cause errors.

U.S. Pat. No. 4,349,318 discloses a blade retaining assembly including acontinuous wire-type retainer, a generally cylindrical retaining plateand a split retainer ring. Annular grooves or recesses are machined outof the rotor disc and the roots of the blades for accommodating theindividual retaining elements.

EP0,761,930A1 discloses a retention plate carried in radially inner andouter slots preventing axial movement of the blade roots in their slots.A locking member is interposed between an adjacent pair of retentionplates to prevent their circumferential movement relative to the disc.The locking member in turn interacts with the disc to anchor itself tothe disc.

It can be seen from above mentioned reference that the current axialretention systems either need further work during the assembly processor have a complex structure, which cause expensive cost of the productand higher likelihood of failures.

SUMMARY

It is an object of the present invention to provide a turbine blade witha simple locking member for axial fixation of the blade relative to therotor disc.

It is another object of the present invention to provide a fail-safesolution during assembly process of the locking member.

The objects are achieved by a blade of turbine, comprising an aerofoil,a platform and a root portion configured to be slidingly received inmounting slots of a rotor disc. The blade further comprises a lockingmember disposed on the root portion and engaged with the rotor disc tomake axial fixation of the blade to the rotor disc.

According to one possible embodiment of the present invention, thelocking member is a locking pin disposed between the root portion andthe rotor disc, the locking pin comprising a first protrusion to engagewith a first groove in the root portion and a second protrusion toengage with a second groove in the rotor disc.

According to one possible embodiment of the present invention, the firstand second protrusions are arranged at one end of the locking pin to bereceived by the first and second groove respectively.

According to one possible embodiment of the present invention, thelocking pin comprises a third protrusion at the other end thereof toabut on a component arranged next to the blade in the axial direction ofthe rotor.

According to one possible embodiment of the present invention, thecomponent comprises a heat shield with an anti-rotation member to engagewith the third protrusion of the locking pin.

According to one possible embodiment of the present invention, theanti-rotation member is sized and positioned so that the anti-rotationmember is engaged with the third protrusion of the locking pin as thefirst and second protrusions of the locking pin are engaged with thefirst and second grooves respectively.

According to one possible embodiment of the present invention, thelocking member or the locking pin is disposed at the both sides of theroot portion.

With the technical solution of the present invention, it provides ablade with simple and cost effective axial locking system to make axialfixation of the blade relative to the rotor disc, and also a fail-safesolution during assembly process.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now to be explained more closely by means ofdifferent embodiments and with reference to the drawings.

FIG. 1 shows a schematic perspective view of a blade assembly of turbinewith a locking pin according to embodiments of the present invention;

FIG. 2 shows a front view of the blade assembly in FIG. 1; and

FIG. 3 shows a cross-section side view of the blade assembly.

DETAILED DESCRIPTION

FIG. 1 shows a schematic view of a blade assembly of turbine accordingto embodiments of the present invention. The blade 100 comprises anaerofoil 111, a platform 112 and a root portion 101. The “fir tree” typeroot portion is configured to be received in the mounting slots of arotor disc 102. To show a complete root portion 101, the rotor disc 102is not shown in FIG. 1, but can be seen from FIG. 3, which shows a crosssection view of the assembly of the root portion 101 and the rotor disc102.

According to an embodiment of the present invention, the blade 100further comprises a locking member disposed on the root portion 101 andengaged with the rotor disc 102, so as to make axial fixation of theblade relative to the rotor disc 102.

In a preferable embodiment of the present invention, the locking memberis embodied as a locking pin 106 as shown in FIG. 1. The locking pin 106is disposed between the rotor portion 101 and the rotor disc 102, whichcan be seen from the cross-section view of FIG. 3. With reference toFIG. 1 and FIG. 2, a first protrusion 107 and a second protrusion 108are respectively disposed on the locking pin 106 in the radialdirection. A first groove 104 is arranged on the root portion 101 toreceive the first protrusion 107; a second groove 105 is arranged on therotor disc 102 to receive the second protrusion 108.

In a preferable embodiment of the present invention, the firstprotrusion 107 and the second protrusion 108 are arranged at one end ofthe locking pin 106 in the radial direction. The first groove 104 andthe second groove 105 are respectively formed on the root portion 101and the rotor disc 102 at the corresponding position to receive thefirst protrusion 107 and the second protrusion 108. However, it shouldbe noticed by those skilled in the art that the two protrusions are notnecessarily arranged at the same end of the locking pin 106. Forexample, the protrusions 107, 108 may also be staggered along the axialdirection of the locking pin 106, as long as they are received in thecorresponding grooves respectively.

In a preferable embodiment of the present invention, a third protrusion109 is arranged at the other end of the locking pin 106 opposite to theone end where the protrusions 107,108 is disposed. As shown in FIG. 1, aheat shield 103 is arranged next to the root portion 101 of the blade inthe axial direction. The heat shield 103 comprises an anti-rotationmember 110. The anti-rotation member 110 is sized and positioned so thatit is engaged with the third protrusion 109 of the locking pin 106 asthe first and second protrusions 107 and 108 of the locking pin 106 areengaged with the first and second grooves 104 and 105 respectively.

During the assembling process, after the installation of the blade 100and the rotor disc 102, the locking pin 106 will be inserted between theroot portion 101 and the rotor disc 102. After inserted, the locking pin106 needs to be rotated by a certain degrees so that the first andsecond protrusions 107 and 108 can be locked into the correspondinggrooves 104 and 105, respectively. However, as the protrusions 107, 108and grooves 104, 105 may not be visible after insertion of the lockingpin 106, it is difficult to evaluate whether the pin is installed inposition. This issue can be solved by arrangement of the anti-rotationmember 110 and its engagement with the third protrusion 109 of the pin106 as mentioned above, in which case the anti-rotation member 110 mayalso function as position element for the locking pin 106. Inparticular, after the locking pin is installed, the heat shield 103 willbe assembled in axial direction next to the root portion 101. However,if the locking pin 106 is not in position, the anti-rotation member 110will be stuck on the third protrusion 109. Then, the heat shield 103cannot be assembled in position. Only when the locking pin 106 isrotated into lock position, the heat shield 103 can be installedcorrectly with the anti-rotation member 110 being engaged with the thirdprotrusion 109. Thus, a fail-safe feature for assembling the locking pinis achieved.

It should be noticed by those skilled in the art that the anti-rotationmember may also be arranged on other components than the heat shield asfar as the fail-safe feature for assembling the locking pin is achieved.

Additionally, as shown in FIG. 3, the locking pins 106 can be disposedat the both sides of each root portion 101.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

1. A blade of turbine, comprising an aerofoil, a platform, a rootportion configured to be slidingly received in mounting slots of a rotordisc, and a locking member disposed on the root portion and engaged withthe rotor disc to make axial fixation of the blade to the rotor disc. 2.The blade of claim 1, wherein the locking member is a locking pindisposed between the root portion and the rotor disc, the locking pincomprising a first protrusion to engage with a first groove in the rootportion and a second protrusion to engage with a second groove in therotor disc.
 3. The blade of claim 2, wherein the first and secondprotrusion are arranged at one end of the locking pin to be received bythe first and second groove respectively.
 4. The blade of claim 2,wherein the locking pin comprises a third protrusion at the other endthereof to abut on a component arranged next to the blade in the axialdirection of the rotor.
 5. The blade of claim 4, wherein the componentcomprises a heat shield with an anti-rotation member to engage with thethird protrusion of the locking pin.
 6. The blade of claim 5, whereinthe anti-rotation member is sized and positioned so that theanti-rotation member is engaged with the third protrusion of the lockingpin as the first and second protrusions of the locking pin are engagedwith the first and second grooves respectively.
 7. The blade of claim 1,wherein the locking member is disposed at the both sides of the rootportion.
 8. The blade of claim 2, wherein the locking pin is disposed atthe both sides of the root portion.